In preparation of an exfoliated MoS.sub.2 catalyst, supported on alumina particles of 300 Angstroms in diameter (Alon Gama-Alumina), an increase in methanation activity by a factor of 4 was achieved by the inventors, and others, as compared to the commercial catalyst (Harshaw 500 E). Co-pending application Ser. No. 855,065, filed Apr. 23, 1986, discloses this subject matter. In general, in order to deposit MoS.sub.2 on the alumina support, the exfoliation technique was used to separate the layers of the layered compound MoS.sub.2 into single layers in suspension. Then by selection of a proper promoter, the MoS.sub.2 single layers and the promoter ions together were deposited onto the alumina support.
Exfoliation, of course, occurs only with layer compounds such as MoS.sub.2, WS.sub.2, TiS.sub.2, etc., for it requires a high density of material such as lithium to intercalate between the layers, a process not possible with non-layered materials such as alumina.
It was during the deposition of the exfoliated MoS.sub.2 onto a porous chi-alumina support that we discovered another process by which the porous chialumina was apparently converted to a new transition alumina and then fractured into ultra-fine particles. The attempt was made, at the beginning, to use this coarse but porous (8 nanometers in pore size) chialumina under the same preparation conditions as it was used for 300 Angstroms Alon alumina, but it was found that the single layers of MoS.sub.2 simply coated the outside surface of the porous alumina particles and did not penetrate into the pores. Thus, the pores were blocked, the extra area available from the pores was lost, and the catalyst was effectively "dead". This interpretation was supported by Co.sub.2 absorption measurements which indicated that the exposed area of the Al.sub.2 O.sub.3 decreased from 286 m.sup.2 /g to 32 m.sup.2 /g when exfoliated MoS.sub.2 was deposited.